And if Bond didn't kill the rest? Where would you rather be, out in the open or trapped in a tunnel?
Worth mentioning who we're talking about here as well, an old gamekeeper who at best might have had to deal with the odd poacher from time to time, and an old woman who, for all that she's head of MI6, we have no indication was every a field operative (she can't even shoot straight). Oh yes, and she was wounded, so add pain/shock into the equation.
Q plugging Silva's laptop in is stupidity beyond belief, two old people well out of their comfort zone using a torch to traverse dangerous ground in the dark might not be the smartest move, but it is at least understandable.